Age softening?...so soon???

I mixed up a batch of 80/20 and added 12% pewter by accident(was planning on trying 6%) on 5/18/18. I tested the alloy with my Lee tester a few days after I casted it. The boolit had BH at 13.4.

Since I had good luck with the above alloy I mixed up another batch of 30 lbs of it a few days ago and made some test boolits to check BH. The first one measured .6 twice which was a little hard. I then grabbed another test boolit that measured 6.2 and 6.3 which is right on the money at 13.4.

Here's where it got interesting...I then tested the same boolit I made on 5/18/18 that still had the original dimple it that measured 13.4 BH. I made two more separate dimples in it. Both the dimples measured 7.0 which means the BH dropped to 10.4!

I thought it took a lot longer to age soften like over a year to years?

My mix consists of 80% ACCOWW, 20% lead flooring which tested at 5 BH, and I added 12% pewter to the total weight. I just tested these boolits a few weeks ago and had some great results with expansion. Guess I'll have to let my boolits sit for a couple months with this alloy before using them to hunt with. After testing different BH's a few weeks ago I already know my boolitss are not going to group the same with the harder alloy. I'm just going to have to wait till it settles.

Why did the BH drop 3 points in 2 months?

Found this article on tin age softening...

http://www.lasc.us/castbulletalloy.htm


Waiting for one the experts to chime in to tell me if this is normal for 2 months time?

Have you confirmed the repeatability of your hardness measuring device with a known alloy?

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Originally Posted by dondiego

Have you confirmed the repeatability of your hardness measuring device with a known alloy?

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I tested my 16:1 and got the same BH measurement that I always get. Ialso grabbed a few more boolits I casted on 5/16 and they also measured soft at 10.4.

The above article I tagged it said the more tin used the faster the alloy will soften. At 12% could this be the issue of loosing 3 points so fast. I never checked my alloy after a couple days time so maybe as the article states it dropped from 13.4 to 10.4 in a month?

You need only 2% Sn max for any booilt you cast!!!! Any more wastes the precious metal and leads to the possible weird hardness shifting you are seeing.

Stick with 1-2% Sn for fill purposes like the rest of us. Sn lowers the surface tension of the alloy mix for better mold fill properties. Sn should not be used for hardness increase. That is what Sb is for.

Bangerjim

Thanks for the heads up Jim. I wanted to try 6% pewter since I read in an old post 6% helped with hollow point expansion using a harder alloy mix to keep the boolit together instead of shedding its hp pedals...which this alloy mix did a great job when I tested it. I just screwed up and calculated wrong dumping in 12%.

What dose t make sense is I mixed 16:1 and it literally dropped out of my mold at 7.5 BH and has been the same hardness ever since. I would assume 12/1 and above is where things go whacky?

Think I figured out my problem. I tested my alloy today. Measured 5.8 with my Lee tester which is telling me 15.4 BH. I used my new microscope mount to hold it still which I think helped as well. I then took one of the boolits I haven't shot yet that I made a couple months ago and tested it instead of the one I filed originally to test. It tested at 5.8.

I believe I accidentally put my 50/50 mix test boolit in the wrong bag that I had labeled 80/20. Makes sense because my 50/50 tests at 10.5 BH.

Whoops!?